Covered flange brace and flange brace cover

ABSTRACT

A building roof structure includes rafters, purlins, braces, and a suspension fabric. The suspension fabric, which may be part of a fall protection system, insulation support system, and/or vapor barrier system, extends across a bay or other portion of the roof structure such that the suspension fabric is above the rafters and below the purlins. The braces connect at least some of the purlins to at least some of the rafters, and each brace extends through a corresponding slit or other opening in the suspension fabric. Brace covers are provided for some or all of the braces to conceal the fabric opening, to facilitate sealing around the brace near the fabric opening, and/or to provide support for the suspension fabric near the fabric opening.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/951,505 filed Mar. 11, 2014, the entirety of thepreceding application being incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

This invention relates to buildings, building components, buildingsubassemblies, and building assemblies, and to methods of constructingbuildings. The invention has particular application to building roofstructures that incorporate rafters, purlins, braces that connectrafters to purlins (e.g. to enhance structural integrity), andsuspension fabrics. The suspension fabric may be part of a fallprotection system, part of an insulation support system, and/or part ofa vapor barrier system. The invention also relates to associatedarticles, systems, and methods.

From time to time, injuries occur during the construction of buildings,including to workers involved in such construction. Workers who areinvolved, in particular, in the construction of roof structures forbuildings are at risk of injury that may result from falling from anelevated height. Standard and required systems and practices have beendeveloped to protect such workers, for example to catch and support themif/when they fall. These systems and practices are referred to as fallprotection systems.

One known fall protection system is a passive system wherein a fabric,such as a solid sheet, a woven sheet, or a net-like material, issuspended at or below the work area, optionally supported by a grid ofcrossing support bands, far enough above any underlying supportingsurface to catch and support a worker who falls, thereby to act as apassive fall-protection system.

The Occupational Safety and Health Administration (OSHA) in the U.S. hasdefined a drop test procedure whereby such a passive fall protectionsystem can be tested. According to the test procedure, a 400 poundweight is dropped onto the fall protection system under statedconditions to determine whether a given system meets the required safetystandards. For purposes of complying with government regulations, anysystem used as a fall protection system need only meet the OSHA-mandatedstandards related to dropping such 400 pound weight. Of course, the realhumanitarian objective is to prevent worker injuries if/when a workerfalls from an elevated work location. Thus, any fall protection systemwhich is effective to catch and safely hold a falling worker hasoperational value, even If such system does not meet OSHA standards.

According to one practice currently in use in the metal buildingindustry, and intended to meet government fall protection standards, apurported fall protection system uses crossing longitudinal and lateralmetal bands extending under the eave, under the ridge, and under theintermediate purlins of the roof structure of the building, and a fabricis installed above the bands and under the purlins, extending across theentirety of a respective bay of the building being constructed, therebyproviding a suspended fabric intended to catch and support a fallingworker in that bay. Insulation is ultimately installed on the topsurface of the fabric whereby the fabric ultimately functions both asthe vapor barrier portion of the building ceiling insulation system inthe finished building and as a catch-and-support fabric in the fallprotection system.

In some cases, the design of a building roof structure calls for flangebraces to be installed between the rafters and purlins of the buildingsupport structure. In some cases, a flange brace has a lower end whichattaches to the bottom flange of a rafter, and an upper end whichattaches to a neighboring purlin which is supported by the rafter. Suchflange braces can enhance the structural integrity of the correspondingroof structure of the building.

However, such flange braces can also pose a challenge to theinstallation of a large suspension fabric which extends across the bayof a building roof structure. As such a fabric is unfolded in order toextend the fabric along the length of the bay underneath a set ofsuccessive purlins, the flange braces may present obstacles to suchunfolding and installation of the extended fabric. One known approach tothis situation is to disconnect the upper ends of the braces from therespective purlins so that the suspension fabric can be extended, and,after the fabric is in place, attaching the upper ends of the braces tobottom surfaces of the respective purlins. This approach avoids havingto create a large hole or opening in the suspension fabric that would beneeded to re-attach the upper end of each brace to a more central partof the respective purlin; however, attachment of the brace to the bottomsurface of the purlin can be contrary to the building specification, andis otherwise undesirable from a structural integrity standpoint.

In another known approach, the upper ends of the braces are againdisconnected from the respective purlins, but, after the extendedsuspension fabric is in place in the bay beneath the purlins and abovethe braces, a large opening is cut in the suspension fabric at alocation corresponding to each brace so that the upper end of the bracecan be re-attached to the respective purlin through such opening. Piecesof patch tape are then applied to the lower surface of the suspensionfabric to repair the openings. In some cases, a sealant is also appliedat the repair points, e.g. to restore the ability of the suspensionfabric (as repaired) to act as a vapor barrier. However, the pieces ofpatch tape applied to the suspension fabric are typically visible tooccupants of the building, e.g. after construction of the roof structureand building is complete, and can be highly unattractive. Furthermore,the patch tape can work loose and delaminate over time with normalexpansion and construction of the building components.

Accordingly, there is a need for a novel approach to the challenge ofconstructing building roof structures which incorporate both extendedsuspension fabrics (e.g. as part of a fall protection system, or forinsulation support, or for use as a vapor barrier) and flange braceswhich connect rafters to purlins in the roof structure.

These and other needs are alleviated, or at least attenuated, orpartially or completely satisfied, by novel products, systems, and/ormethods of the invention.

SUMMARY

This invention provides brace covers suitable for use in building roofstructures; systems and combinations involving such brace covers;methods of making and installing such brace covers, systems, andcombinations; and buildings and roof structures which incorporate suchbrace covers, and kits which include a suspension fabric, banding forsupporting the suspension fabric, and brace covers for covering openingsin the suspension fabric through which braces will be extended.

For example, a building roof structure may include rafters, purlins,braces, and a suspension fabric. The suspension fabric, which may bepart of a fall protection system and/or part of an insulation supportsystem and/or part of a vapor barrier system, extends across a bay orother portion of the roof structure such that the suspension fabricextends onto the tops of the rafters but below the purlins. Bracesconnect at least some of the purlins to at least some of the rafters,and each brace extends through a corresponding slit or other opening inthe suspension fabric. Brace covers are provided for some or all of thebraces to conceal the fabric opening, to facilitate sealing around thebrace near the suspension fabric opening to prevent passage of airthrough the suspension fabric opening, and/or to provide support for thesuspension fabric near'the suspension fabric opening.

In a first family of embodiments, the invention comprehends a buildingroof structure, comprising rafters and purlins, the purlins extendingtransversely across the rafters such that the rafters support thepurlins; a suspension fabric extending across the roof structure suchthat the suspension fabric extends across the tops of the rafters andbelow the purlins; braces connecting at least some of the purlins to atleast some of the rafters, each brace, and the respective purlin towhich such brace connects, defining a brace/purlin combination, and eachbrace extending through a corresponding suspension fabric opening in thesuspension fabric; and for each of at least some of the brace/purlincombinations, a brace cover having a cover opening through which thebrace extends, the brace cover being disposed such that a portion of thesuspension fabric is between the brace cover and the purlin.

In some embodiments, for at least some of the brace/purlin combinations,the purlin has a lower flange, and the brace cover is attached to thelower flange of the purlin.

In some embodiments, for at least some of the brace/purlin combinations,the purlin has a central web disposed between a purlin upper flange anda purlin lower flange, and the brace is attached to the central web ofthe purlin.

In some embodiments, at least some of the brace/purlin combinationsfurther comprise a sealant applied around the brace and optionally intothe cover opening in order to provide a barrier against ambient air flowthrough the cover at the cover opening.

In some embodiments, for at least some of the brace/purlin combinations,the brace cover has a perimeter which encompasses the suspension fabricopening.

In some embodiments, at least some of the brace/purlin combinationsfurther comprise one or more pieces of tape applied to the suspensionfabric to patch, to thereby at least partially close, the suspensionfabric opening.

In some embodiments, a sealant bridges and seals a space between thebrace cover and the suspension fabric.

In some embodiments, the sealant defines a closed loop path which isspaced from the suspension fabric opening, which closed loop pathencompasses the suspension fabric opening.

In some embodiments, a perimeter of the brace cover defines a closedloop path which encompasses the closed loop path of the sealant.

In some embodiments, for at least some of the brace/purlin combinations,the brace cover comprises a plate, and the plate has a plate aperturewhich forms at least a portion of the cover opening.

In some embodiments, the plate of at least one of the brace covers has a1-piece construction.

In some embodiments, the plate of at least one of the brace covers has a2-piece construction.

In some embodiments, each plate which has the 2-piece construction has afirst plate piece attached to a second plate piece, and the plateaperture in each such plate is partially defined by said first platepiece and partially defined by said second plate piece.

In some embodiments, plate aperture has a first L-shaped profile and,when the plate and brace are installed such that the plate is attachedto the associated purlin and the brace is attached to the associatedrafter and purlin, the plate aperture defines a reference plane, and across-section of the brace in the reference plane has a second differentL-shaped profile.

In some embodiments, the L-shaped profile has first and second legs, andwherein the first leg is at least 1.5 inches long and the second leg isat least 1.5 inches long.

In some embodiments, the brace cover of at least some of thebrace/purlin combinations also comprises a fabric piece attached to theplate and, when installation of the brace cover has been completed, thecover opening further comprises a fabric piece opening in the fabricpiece, further comprising a sealant applied at a junction of the braceand the brace cover at the cover opening and optionally into the coveropening in order to provide a barrier against ambient air passingthrough the cover opening.

In some embodiments, the cover plate has first and second opposing majorsurfaces, the first major surface facing the purlin, and wherein thebrace cover further comprises a fabric piece which covers the secondmajor surface of the plate.

In some embodiments, the fabric piece is made of a same material as thesuspension fabric.

In a second family of embodiments, the invention comprehends a buildingroof structure, comprising building structural roof elements includingat least first and second rafters, a space between the first and secondrafters defining a first distance between the first and second rafters,each rafter having a top, and opposing first and second ends, the roofstructure further comprising an eave, having a length, and extendingbetween the first ends of the first and second rafters, a ridge, havinga length, and extending between the second ends of the first and secondrafters, and a second distance between the eave and the ridge, the eaveand the ridge being disposed on, extending transverse to, and beingconnected to, the tops of the first and second rafters, and a pluralityof intermediate purlins extending between the first and second raftersand spaced from each other between the eave and the ridge, theintermediate purlins being disposed on, and extending transverse to, thetops of the first and second rafters, the building roof structurefurther comprising a first set of support bands extending from the firstrafter to the second rafter and being connected to the buildingstructural roof elements, the first set of support bands being spacedalong the lengths of the first and second rafters; a second set ofsupport bands extending from the eave toward the ridge and under theintermediate purlins, the second set of support bands having first andsecond end portions and being spaced from each other between the firstand second rafters; a suspension fabric overlying, and being supportedby, the first and second sets of support bands, the suspension fabricbeing securely attached to structural members of the building, aplurality of braces which collectively connect at least some of theintermediate purlins to one or both of the first and second rafters,each brace extending through a corresponding fabric opening in thesuspension fabric; and for each brace which connects a given purlin to agiven rafter, a brace cover having a cover opening through which therespective brace extends, the brace cover being attached to the givenpurlin and having a perimeter which encircles the fabric opening throughwhich the brace extends.

In a third family of embodiments, the invention comprehends a bracecover suitable for use in a building roof structure which includesbuilding roof structure braces, the brace cover comprising a platehaving a thickness of at least 0.01 inch, and having an L-shapedaperture, the L-shaped aperture having a first leg at least 1.5 incheslong and a second leg at least 1.5 inches long, such that the L-shapedaperture is sized to receive a building roof structure brace; and afabric piece attached to the plate such that the fabric piece covers theaperture, the fabric piece also being imperforate at least in a regioncorresponding to the aperture such that the fabric piece seals theaperture.

In some embodiments, the second layer comprises a fabric piece made of amaterial suitable for use as a suspension fabric in a building fallprotection system.

In some embodiments, the second layer has a layer perimeter and theplate has a plate perimeter, and wherein the second layer perimetersubstantially matches the plate perimeter.

In some embodiments, the second layer is imperforate.

In a fourth family of embodiments, the invention comprehends a method offabricating a building roof structure, comprising providing an initialbuilding structure which includes columns, rafters supported by thecolumns, purlins supported by the rafters, and braces which connect atleast some of the rafters to at least some of the purlins, each bracehaving an upper end which attaches to an associated purlin; detachingthe upper ends of the braces from the associated purlins; laying out asuspension fabric across the roof structure above the rafters and belowthe purlins; and for a given brace, cutting a suspension fabric openingin the suspension fabric near the brace and the associated purlin,thereby to define a cover opening; guiding the upper end of the bracethrough the fabric opening in the suspension fabric, and re-attachingthe upper end of the brace to the associated purlin; and attaching abrace cover to the associated purlin with a portion of the suspensionfabric disposed between the brace cover and the purlin, the brace coverhaving a cover opening through which the brace extends.

In some embodiments, for a given brace, the attaching comprises passingthe upper end of the brace through the cover opening before re-attachingthe upper end of the brace to the associated purlin.

In some embodiments, the method further comprises, before the attachingthe brace cover to the associated purlin, providing the brace cover inan initial state, the brace cover in the initial state including a plateand a fabric piece, the plate having a plate aperture, and the fabricpiece being attached to the plate such that the fabric piece covers theplate aperture, the fabric piece being imperforate at least in a regioncorresponding to the plate aperture such that the fabric piece seals theplate aperture against free flow of ambient air through the fabricpiece; and slitting the fabric piece in the region corresponding to theplate aperture to provide the cover opening.

In some embodiments, the method further comprises, for a given brace,after re-attaching of the upper end of the brace to the associatedpurlin, and before attaching the brace cover to the associated purlin,sliding the brace cover upwardly along the brace toward the associatedpurlin.

In some embodiments, for a given brace, assembling the brace cover aboutthe brace and thereby defining a brace cover opening through which thebrace extends.

In some embodiments, for a given brace, the brace cover comprises aplate having a plate aperture, the plate aperture being at least aportion of the cover opening, the plate also having a 2-piececonstruction comprising a first plate piece and a second plate piece,and wherein the assembling of the brace cover about the brace comprisesjoining the two plate pieces to each other and thereby forming the plateaperture about the brace.

In some embodiments, each brace cover has a perimeter and wherein, for agiven brace, the attaching of the brace cover to the associated purlincomprises positioning the brace cover so that the perimeter of the bracecover encompasses the fabric opening.

In some embodiments, the invention further comprises, for a given brace,sealing the brace cover to the suspension fabric using a sealant in aclosed loop path which is laterally spaced from the fabric opening andwhich encompasses the fabric opening.

In some embodiments, the invention further comprises, for a given brace,sealing the cover opening from ambient air flow by applying a sealant ata junction of the brace and the brace cover at the cover opening andoptionally into the cover opening in order to provide a barrier againstambient air flow through the cover opening.

In a fifth family of embodiments, the invention comprehends a method ofinstalling a brace cover on a brace in relation to a building roofstructure, the method comprising providing a brace cover in an initialstate, the brace cover in the initial state including a plate and afabric piece, the plate having a plate aperture, and the fabric piecebeing attached to the plate such that the fabric piece covers the plateaperture, the fabric piece being imperforate at least in a regioncorresponding to the plate aperture such that the fabric piece seals theplate aperture; providing a brace having a first end; forming a slit inthe fabric piece in the region corresponding to the plate aperture; andpassing the first end of the brace through the slit and through theplate aperture.

In some embodiments, the brace has a second end opposite the first end,and wherein the second end is secured to building roof support structureunder the building roof structure during the passing of the first end ofthe brace through the slit and through the plate aperture.

In some embodiments, the brace has an L-shaped cross-section, andwherein the forming of the slit forms the slit in an L-shapeconfiguration.

In a sixth family of embodiments, the invention comprehends a suspensionfabric kit, comprising a length of support banding suitable forextending a first set of support bands from a first rafter of a buildingto a second rafter of such building, and a second set of support bands,for crossing the first set of support bands and extending from an eaveof such building, under intermediate purlins, to a ridge of suchbuilding; a suspension fabric suitable for extending from such firstrafter to such second rafter and from such eave to such ridge, with thefirst and second sets of support banding supporting the suspensionfabric; and a plurality of brace covers adapted and configured to extendabout braces which are secured to ones of such rafters and ones of suchpurlins, and wherein such braces extend through apertures in the bracecovers, the brace covers, in combination with sealants applied to thebrace covers, bridging edges of the brace cover apertures and surfacesof such braces, and thereby providing a barrier against flow of ambientair through the respective cover apertures.

Related methods, systems, and articles are also discussed.

These and other aspects of the present application will be apparent fromthe detailed description below. In no event, however, should the abovesummaries be construed as limitations on the claimed subject matter,which subject matter is defined solely by the attached claims, as may beamended during prosecution.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are described hereinafter, byway of example only, with reference to the accompanying drawings,wherein:

FIG. 1 is a perspective view, from above the eaves, of a typical metalbuilding support structure, including columns, rafters, eaves, ridges,and intermediate purlins.

FIG. 2 is a perspective view, from above the roof, of part of a bay of ametal building, showing columns, rafters, purlins, an eave, and agrid-work of crossing bands.

FIG. 3 is a perspective view as in FIG. 2 showing a suspension fabricpartially extended over the band grid-work and under the eave and underthe purlins, in a single bay.

FIG. 4 is a diagrammatic end view of a roof structure of a metalbuilding, showing longitudinal band spacing with respect to the eaves,the ridges, and the intermediate purlins.

FIG. 5 is an edge view showing a lateral band fastened, attached, to thebottom flange of the eave.

FIG. 6 is a cross-section of an intermediate purlin, and a Tek screw,with washer, positioned to extend the screw through the fabric and intothe purlin bottom flange.

FIG. 7 is a perspective view from below a fall protection system,showing a purlin mounted on one of the rafters, also showing the lateralbands and the longitudinal bands collectively supporting the suspensionfabric across a bay.

FIG. 8 is a perspective view of a flange brace.

FIG. 9 is a perspective view of an apertured plate which may serve as abrace cover.

FIG. 10 is a perspective exploded view of a second embodiment of a bracecover.

FIG. 11 is a perspective view from below an inverted brace cover likethat of FIG. 10.

FIG. 12A is a cross-section of the brace cover of FIG. 11 along line12A-12A.

FIG. 12B is a cross-section of the brace cover of FIG. 12A after cuttingan opening in the fabric piece.

FIGS. 13A through 13G are a sequence of schematic side views of aportion of a building structure, illustrating how building elementsincluding a rafter, a purlin, and a flange brace appear from thisvantage point during different steps in a process which includesinstalling a suspension fabric, attaching the brace to the purlinthrough the suspension fabric, and installing the brace cover.

FIG. 14 is a schematic cross-section taken along line 14-14 in FIG. 13F.

FIG. 15 is a schematic cross-section taken along line 15-15 in FIG. 13F.

FIG. 16A is a schematic cross-section taken along line 16A-16A in FIG.13F.

FIGS. 168 and 16C are schematic cross-sections similar to FIG. 16A butfor alternative brace cover embodiments.

FIGS. 17A through 17C show a sequence of schematic views that lookdownward on a portion of a building structure from a plane which passesthrough two purlins below their upper flanges, illustrating how buildingelements including rafters, purlins, and a suspension fabric appear fromthis vantage point during different steps in a process of attachingflange braces to the purlins through the suspension fabric.

FIGS. 18A through 18G show a sequence of schematic views which lookupward from below at a portion of a suspension fabric in a building neara location on a purlin where a flange brace attaches to the purlin,illustrating how the suspension fabric and related building elementsappear from this vantage point during different steps in a process whichincludes attaching a flange brace to the purlin through the suspensionfabric and installing a brace cover.

FIGS. 19A and 198 are upwardly-looking plan views of a 2-piece plate foruse in the disclosed brace covers, FIG. 19A showing the two plate piecesof the plate separated and FIG. 19B showing the two plate pieces joinedtogether to form a plate aperture.

FIGS. 20A and 20B are upwardly-looking plan views similar to FIGS. 19Aand 19B but for another embodiment of a 2-piece plate.

FIGS. 21A and 21B are upwardly-looking plan views similar to FIGS. 19Aand 19B but for still another embodiment of a 2-piece plate.

FIG. 22 is an upwardly-looking plan view of a 2-piece plate similar toFIGS. 19A and 19B, but the two plate pieces are pivotably connectedtogether so that one piece can rotate relative to the other, and adetent mechanism is provided to temporarily lock to two pieces together,until screws can secure the closed combination to the flange of apurlin.

The invention is not limited in its application to the details ofconstruction, or to the arrangement of the components or to the methodsof construction, set forth in the following description or illustratedin the drawings. The invention is capable of other embodiments or ofbeing practiced or carried out in various other ways. Also, it is to beunderstood that the terminology and phraseology employed herein is forpurpose of description and illustration and should not be regarded aslimiting. Like reference numerals are used to indicate like components.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The description below, begins with a discussion in FIGS. 1-7 of certainmetal buildings and certain fall protection systems for such buildings,so as to provide context for later discussion relating more specificallyto flange braces and brace covers for use with the flange braces. Thereader will understand that although the disclosed brace covers can beused in the fall protection systems which are specifically described,the brace covers can also be used in other fall protection systems, aswell as in other building structures that may not include a fallprotection system.

FIG. 1 illustrates the primary structural members of a typical metalbuilding 10 having first and second roof slopes 12A and 128. Verticalsupport for the structural elements of the roof, designated generally as12, is provided by upstanding columns 14 positioned along side walls andend wails of the building. Rafters 16 overlie the tops of the columnsand are supported by the columns. Rafters 16 span the width of thebuilding, creating a series of open spaces between rafters 16, the openspaces being commonly referred to as “bays” 18 in the construction arts,the bays representing distances between respective ones of the rafters.Each rafter has an upper surface 16A, and opposing first 16B and second16C ends.

According to the embodiments illustrated in FIGS. 1-4, eaves 20,expressing “C”-shaped cross-sections, are positioned at the down-slopeends of the rafters 16. Lengths of the eaves extend along the length ofthe building, above the outer wall of the building, The eaves providelateral support to the skeletal structure of the building betweenrespective ones of the columns 14, at the outer building wall. A giveneave extends between the first ends 16B of respective ones of therafters.

Ridge members 22, expressing “Z”-shaped cross-sections as illustrated inFIG. 4, have lengths which overlie, and are attached to, the uppersurfaces of rafters 16. The ridge members are positioned at the up-slopeends of the rafters, and run the length of the building parallel to theeaves, typically above the central portion of the building. The ridgemembers provide lateral support to the skeletal structure of thebuilding between respective ones of rafters 16, typically at an internalportion of the building, away from the building side walls in theillustrated embodiments. A given ridge member extends between the secondends 16C of the respective ones of the rafters. Where the roof has asingle pitch direction, the ridge can be positioned proximate one of theouter walls of the building.

The ridge members and the eave members overlie, extend transverse to,and are attached to, the upper surfaces of the respective rafters 16,and are spaced from each other by distances which generally correspondto the lengths of the respective rafters between ends 16B and 16C.

Intermediate purlins 24 express “Z”-shaped cross-sections. Theintermediate purlins overlie, extend transverse to, and are attached to,upper surfaces 16A of the respective rafters. Purlins 24 are spaced fromeach other along the lengths of the rafters. The purlins extend parallelto each other and parallel to any ridges and eaves and, overall, spanthe length of the bay, whereby the purlins are displaced from each otherand from any ridges and eaves along the spaces between the respectiveeave and the ridge.

As shown in FIG. 2, a fall protection support system includes asupporting grid-work formed by crossing elongate steel bands, includinglongitudinal support bands 26 and lateral support bands 28. Supportbands 26, 28 of the grid-work are supported by various ones of thebuilding structural members, as described herein, and the collectivegrid-work generally defines an imaginary plane, extending into the sheetof the drawing illustrated in FIG. 4. Such imaginary plane extendsparallel to a set of imaginary straight lines, spaced from each otherand extending between the lower surfaces of the eaves 20, the ridge 22,and intermediate purlins 24, and further extending parallel to imaginarystraight lines which connect the upper surfaces of the rafters.

Support bands 26, 28 support a high strength fabric 32, the fabric beingshown partially unfolded in FIG. 3 and, in FIG. 4, the fabric issuggested by the dashed line under the eave, ridge, and intermediatepurlins, and above longitudinal bands 26, bands 26 being shown in FIG. 4in end view. Fabric 32 in the illustrated embodiments also serves as avapor barrier for the insulation system which is ultimately installed atthe roof of the building.

Starting with the structural skeleton of the building as illustrated inFIG. 1, a fall protection system may be installed generally as follows.Longitudinal metal bands 26 are extended from the upper surface of afirst one of the rafters to the upper surface of a second one of therafters at angles which are typically, but not necessarily,perpendicular to the respective rafters. The number of longitudinalbands 26 depends to some degree on the distance between the respectiveones of the intermediate purlins 24. Typically, only a singlelongitudinal band 26 is used between each pair of next-adjacent purlins24. However, in certain systems, two or more longitudinal bands may beused where such additional band use may be cost-effective and/or whenuse of such additional band may be needed in order to satisfy therespective governmental standard. Of course, the greater the number ofbands used, the greater the cost of the band system. Accordingly, theuser is motivated to have the system engineered so as to use as few ofsuch longitudinal bands as possible while meeting the required safetystandards.

A length of a given longitudinal band 26 extends across a given bay andis extended across the upper surface of each rafter overlain by therespective band, and is attached to the upper surfaces, or othersurfaces, of the respective rafters. Where the longitudinal band 26extends across multiple bays, the longitudinal band is secured, forrestrained longitudinal movement, to the upper surfaces of those rafterswhich are most remote from one another. Optionally, but not necessarily,the longitudinal band may be secured to one or more intermediaterafters.

Longitudinal bands 26 are fastened to the rafters, rake channels, orrake angle(s) (not shown) which correspond with the end portions of thebands, by conventional attachment means such as by self-drilling screws.Longitudinal bands 26 are pulled tight between the rafters so as to, inpart, and at this stage of installation, begin to define theafore-mentioned band grid, and the imaginary plane of support providedby the band grid, immediately under the intermediate purlins. Bandattachment tools, known in the art, may be used in attaching the bands,either temporarily or permanently, to the rafters or rake channels, thusto instill a suitable, conventionally known, level of tension in bands26 as the bands are being installed.

Each eave has a top flange 34, a bottom flange 36, and an upstanding web38 extending between the top and bottom flanges, and connecting the topflange to the bottom flange. The top and bottom flanges are arrangedsuch that the profile of the eave defines a generally “C”-shapedstructure, perhaps best seen in FIG. 5.

While the eave profiles shown define generally perpendicular turnsbetween the flanges 34 and 36, and upstanding web 38, actual eaveprofiles typically define a modest acute angle (not shown) between thebottom flange and the upstanding web and a corresponding modest obtuseangle (not shown) between the top flange and the upstanding web. Suchacute and obtuse angles adapt the eave to the specific slope of the rooffor which the eaves are designed, while providing that the upstandingweb conforms to the vertical orientation of the respective side wall ofthe building.

Correspondingly, each ridge has a top flange 40, a bottom flange 42, andan upstanding web 44 extending between the top and bottom flanges, andconnecting the top flange to the bottom flange. The top and bottomflanges are arranged such that the profile of the ridge defines a“Z”-shaped structure, as illustrated in FIG. 4.

Similarly, each intermediate purlin has a top flange 46, a bottom flange48, and an upstanding web 50 extending between the top and bottomflanges, and connecting the top flange to the bottom flange. The top andbottom flanges are arranged such that the profile of the respectivepurlin defines a “Z”-shaped structure, illustrated in FIGS. 4 and 6.

Lateral bands 28 are installed after the longitudinal bands 26 are inplace. Lateral bands 28 extend transverse to, typically perpendicularto, the longitudinal bands. Lateral bands 28 generally underlie andsupport longitudinal bands 26. Lateral bands 28 may be first attached tothe respective ridge 22. Bands 28 may be attached to any suitablesurface of the ridge which enables the band to pass, from the locationof attachment, under and in tensioned contact with, the bottom flange ofthe ridge. For example, a lateral band can be attached to the bottomsurface of the bottom flange of the ridge, with intervening fabric 32,and extend from there toward the eave.

As an alternative, one end of a given lateral band can extend upalongside, and be fastened to, the surface of the upstanding ridge web44 which faces away from the eave on the respective slope of the roof.The band passes downwardly alongside web 44, and turns about the edge ofthe bottom flange of the ridge which faces away from the respectiveeave, and then passes under, and in general contact with, the bottomsurface of the bottom flange, again with intervening fabric, and extendsfrom there toward the eave.

As a still further example of attachment of a lateral band to the ridge,the band can be attached to the top surface of the top flange, turnabout the upper edge of the top flange which is away from the respectiveeave, extend from there down toward the bottom ridge flange, turn aboutthe edge of the bottom flange and pass alongside, and in general contactwith, the bottom surface of the bottom flange, and extend from theretoward the eave, again with the fabric between the band and the ridge.

The lateral bands are extended, from the bottom surface of the bottomflange of the ridge toward the respective eave, passing under thelongitudinal bands, and pulled tight to minimize sag in both the lateralbands and the respective overlying longitudinal bands. The so-tightenedlateral bands are in general contact, again with intervening fabric,with the bottom surface of the bottom flange of the respective eave.With the so-tightened lateral bands in contact with the bottom surfaceof the bottom flange of the respective eave, the lateral bands arefastened to the eave so as to maintain the tension in the lateral bands,thus to lift the lateral bands toward the bottom flanges of theoverlying intermediate purlins.

The number of lateral bands 28 to be used between a respective pair ofnext-adjacent rafters, and the spacing between the lateral bands, varieswith the distance between the rafters. Typically, the lateral bands are36 inches to 40 inches apart, optionally up to 48 inches apart in somecases.

Traditional banding stock used for bands 26 and 28 is a hot-dipzinc/aluminum alloy-coated Grade 80 structural steel, 0.023 inch thick,having longitudinal tensile yield strength of at least 93 ksi, suchGrade 80 banding sometimes being referred to in the industry as “fullhard”. Such steel banding is typically about 1 inch wide and continuouslength. Such traditional “full hard” steel banding is available fromSteelscape, A BlueScope Steel Company, Kalama, Wash. as ZINCALUME® SteelGrade 80 (Class 1).

Representative properties of such Grade 80 (Class 1) banding, 0.023 inchthick, from Steelscape are as follows:

-   -   Yield strength—100.1 ksi average, 93.9-104.1 ksi range    -   Tensile strength—102.2 ksi average, 95.4-105.3 ksi range    -   Elongation in 2 inch sample—10% average, 9.6-10.3% range    -   Hardness, Rockwell B Scale—93.4 average, 92-95 range    -   “Ksi” means “thousands of pounds per square inch”.

FIG. 5 shows the attachment of a lateral band to an eave 20 using astandard Tek screw. FIG. 6 shows the impending attachment of the lateralband to an intermediate purlin using a standard Tek screw.

FIG. 7 illustrates that longitudinal bands 26 are supported by lateralbands 28, in that the tightened lateral bands underlie the longitudinalbands. Referring again to FIGS. 2 and 3, it is seen again that thelongitudinal bands are secured against longitudinal movement only atrafters 16.

Certain fabrics are known in the art for use as suspension fabrics inroof insulation systems, and such fabrics may also be acceptable in fallprotection systems, provided for example that the bands used in the bandgrid-work are sufficiently close together. An exemplary fabric for usewith the band grid-work disclosed herein is available as Type 1070 VaporRetarder fabric from Intertape Polymer Group, Bradenton, Fla. The Type1070 fabric is a woven HDPE scrim having the following characteristicsas specified by the fabric supplier:

-   -   Nominal thickness—9 mils (0.23 mm)    -   Nominal weight—4.3 oz/yd² (149 g/m²)    -   Grab Tensile—Warp 136 lb (605 N)/ Weft 126 lb (559 N)    -   Strip Tensile—Warp 100 lb/in (877)/ Weft 90 lb/in (799)    -   Tongue Tear—Warp 50 lb (222 N)/ Weft 45 lb (200 N)    -   Mullen Burst—245 psi (1690 kPa)    -   Moisture vapor transmission—0.02 perms.

A typical bay 18 is about 25 feet wide, between pairs of next-adjacentrafters. Within a given bay, lateral bands 28 extend parallel to eachother, parallel to the respective rafters which define the bay, and aregenerally spaced apart by about 36 inches to 40 inches, but no more than48 inches. Thus, a desired spacing between lateral bands 28 is 36-40inches; but up to 48 inches is accepted where the increase from 40inches e.g. up to 48 inches can reduce the number of bands.

A leading edge of fabric 32 can be placed inside the eave. A leadingedge of the fabric enters the eave above bottom flange 36, passes acrossthe top of the bottom flange to web 38, passes along the inside surfaceof web 38 and up to upper flange 34 and thence toward the ridge, to theeave opening which faces the ridge. By traversing such path inside thecavity defined inside the eave, the fabric can substantially encase theedge of any insulation which is to be installed on top of the fabric inthe space between the eave and the next-adjacent purlin.

In the alternative, the edge of the fabric, at the eave, can be trappedbetween the lateral banding and the lower surface of the bottom flangeof the eave as suggested in FIGS. 3 and 5.

If/When a falling/dropping impact force arrives on the suspensionfabric, the force received by the suspension fabric has a firstdirectional force component and a second velocity/shock/suddennesscomponent. The force component of the impact is resisted by, absorbedby, the deflection characteristics of the materials in the fallprotection system. The velocity/shock/suddenness component of the impactaddresses the rate at which the respective materials can deflect as theforce of the impact is applied to the respective building elements.

Where a given lateral band 28 is one of the closest lateral bands to thepoint where the impact force is received, a first portion of that force,which is received at the fall protection system, is transferred, asfirst tensile forces, into the respective lateral band and is absorbed,dissipated, at least in part, by tensile elongation of the respectivelateral band.

A second portion of that received force is transferred, by the lateralband to the next-adjacent purlins which are closest to the location ofthe impact.

A third portion of that force is received into the respectivelongitudinal band, or bands, and is absorbed, dissipated, at least inpart, by tensile elongation of the respective longitudinal band orbands.

A fourth portion of that received force is received by the respectivelongitudinal band or bands, and transferred by the longitudinal bands,to the respective rafters 16.

A fifth portion of that received force is distributed about therespective affected area of the suspension fabric. While choosing to notbe bound by theory, the inventor herein contemplates that the fabricabsorbs both a portion of the directional component of the force of theimpact and a velocity/shock/suddenness component of the force of theimpact.

Turning again to the responses of the bands, the tensile forces soimposed on the longitudinal bands and the respective lateral band orbands are distributed along the full lengths of the respectivelongitudinal bands and along that portion of the respective lateral bandor bands which is/are between the two purlins which are next adjacentthe location on the fall protection system where the impact of the dropis received. Thus, the elongation properties of both the longitudinalbands and the lateral bands are utilized in transferring portions of theimpact force to the roof structural elements, namely one or moreintermediate purlins, and optionally to ridges or eaves, and to therafters or rake channel(s) or rake angle(s).

FIG. 7 further shows, in its typical configuration of the fallprotection system of the invention, that lateral bands 28 can, andcommonly are, attached to each purlin in a conventional manner, namelyby screwing a Tek screw 66, with accompanying washer, through a hole inthe lateral band, thence through the suspension fabric, and thencethrough the lower flange of the respective purlin. The suspension fabricis thus trapped between the lower flange of the purlin and therespective washer/screw combination, which tightly clamps the suspensionfabric to the lower surface of the lower flange of the purlin.

Method of Installing Fall Protection System

Installation of a fall protection system may begin after the columns,rafters, ridges, eaves, and intermediate purlins are in place about atleast a given bay. Typically, installation of the fall protection systembegins after erection/emplacement of all of the columns, rafters,ridges, eaves, and purlins.

Installation of the fall protection system begins by installinglongitudinal bands 26. A given longitudinal band is installed byunwinding band material from a roll and extending the band material overthe tops of the respective rafters and across a given bay or bays. Atleast one longitudinal band is extended, between each next-adjacent pairof purlins to at least the next rafter, and is cut to length. Thelongitudinal bands are manually stretched tight with hand tools, and theso-tightened bands are fastened to the respective rafters with Tekscrews. As illustrated in the drawings, the longitudinal bands typicallyextend perpendicular to the rafters, rake channel(s), or rake angle(s).The so-partially-installed, tightened, longitudinal bands extend fromrafter to rafter at generally the height of the tops of the rafters, butsome nominal amount of sag of the longitudinal bands exists between therafters at this stage of installation.

Typically, the purlins are spaced no more than 5 feet apart. A singleband may be installed between each pair of next-adjacent purlins so longas the purlin spacing is no more than the typical maximum of 5 feet.Where the purlin spacing approaches, or exceeds, the typical 5-feetmaximum, an additional longitudinal band 26 may be used in one or moreof the spaces between the purlins.

Once the longitudinal bands 26 have been emplaced and tightened, bandingfor lateral bands 28 is unrolled under the longitudinal bands, and oneend of the banding is secured to the respective ridge or purlin, or toan opposing eave. The lateral banding material is extended to the eaveof the respective bay and then tightened sufficiently to raise both thelateral band and the overlying longitudinal bands into close proximitywith the intermediate purlins. This process is repeated along the widthof the bay, e.g. between the rafters, until the desired number oflateral bands has been emplaced across the width of the bay.

With the band grid system thus temporarily in place, a zigzag-foldedroll of the suspension fabric is elevated to the height of the rafters,typically adjacent a rafter at an end of the building or bay. The fabricis then unrolled on top of the band grid in one of the spaces betweennext-adjacent ones of the purlins such that one end of the fabric facesthe eave and the opposing end of the fabric faces the ridge. The ends ofthe fabric are then pulled, individually, toward the eave and the ridge,working the leading ends of the fabric under the interveningintermediate purlins and above the band grid. The initial phase of theprocess of so-extending the fabric is illustrated in FIG. 3. In caseswhere the building structure includes flange braces that connect atleast some of the rafters to at least some of the purlins, such bracesmay interfere with this process of extending the suspension fabricunderneath purlins to which the braces are attached. Accordingly, inorder for the suspension fabric to be fully laid out across the bay, theupper ends of the braces may need to be detached from their respectivepurlins and bent downwardly to provide an unobstructed space for thesuspension fabric to be stretched across. This is shown below inconnection with FIGS. 13A, 13B, and 13C.

With the fabric having been generally extended the full length and widthof the bay over which the fabric is to be suspended, namely over theband grid and under the intermediate purlins, the lateral bands are thenattached to the intermediate purlins, one self-drilling Tek screwthrough each lateral band and the fabric, at each purlin, typicallybeginning at the ridge and working toward the eave. As a such Tekscrew/washer is driven tight against the bottom surface of the fabric,the fabric is correspondingly driven tight against the bottom surface ofthe lower flange of the purlin. The fabric is thus tightly trappedbetween the washer and the lower flange of the purlin. Screws 66 aredriven through each lateral band 28 at each purlin, fastening thelateral bands directly to the purlins as illustrated in FIG. 7.

Once the attachments to the intermediate purlins have been completed,the temporary attachments of the bands to the eave are released, and thelateral bands are permanently attached to the eave, e.g. using screws 66driven through the lateral bands, e.g. as illustrated in FIG. 5.

Sides of the fabric are then cut around the purlins at each rafter, asknown in the art, and edges of the fabric are secured to the topsurfaces of the rafters such as by adhesive, also as known in the art.

With both the longitudinal and lateral bands so secured to the roofstructure, and with the fabric so secured to the ridge and eave by thelateral bands and secured to the rafters by e.g. adhesive, installationof the fall protection system of the invention is thus complete andready to protect workers who subsequently install other elements of thebuilding while working at the roof elevation; such elements as the roofinsulation and the roof panels.

Suspension fabric 32, which in the preferred embodiment is or includes avapor barrier material, is trimmed to size before installation. Specifictrimming of the suspension fabric 32 in the form of notches may also beperformed before or during installation at locations where purlinscontact the upper surfaces of rafters. A notch in the fabric at such alocation allows the edge of the fabric to more fully cover the topsurface of the rafter immediately adjacent the point of contact with thepurlin, while also allowing the fabric to extend longitudinally acrosssubstantially the entire accessible length (between adjacent rafters) ofthe bottom flange of the purlin. This is shown and described below inconnection with FIG. 17A. The suspension fabric is installed one bay 18at a time and, in the case of large buildings or buildings with highgables, fabric 32 for each half of the bay may be divided at ridge 22and may be installed separately.

The suspension fabric has been cut, prior to installation, to a sizehaving a dimension a few inches longer, at each side and each end, thanthe dimensions of the bay to be overlaid, and is Z-folded for easyspreading above the band grid. For this purpose a zigzag type fold, asshown in FIG. 3, is easiest to work with, although other rolling orfolding arrangements can also be used and are within the scope of theinvention.

The fall protection systems discussed herein can be designed to be ofsufficient strength to catch and support a man's weight, generallybetween 250 and 400 pounds. The system is tested by dropping a 400 lb.weight, with the center of gravity of the weight, before the weight isdropped, being 42 inches above a worker's walking height, thus 42 inchesplus the height of the purlins, namely about 50.5 inches above thefabric. To pass the test, the system must effectively stop the fallingweight at any point in the bay which is so protected. In one testspecified by OSHA, 400 lb. of washed gravel or sand is placed into areinforced bag that can tolerate being dropped repeatedly. The test bagis 30 inches in diameter. The 400 pound bag is hoisted above the fallprotection system to a height of 42 inches above the plane of theintermediate purlins, measuring from the center of the so-filled bag. Acord supporting the weight of the bag is then released, allowing theweight to free fall in one concentrated load. The weight can be droppedonto any part of the fall protection system to test different areas.

Having generally described exemplary building and roof structures andpassive fall protection systems and related systems and components, wenow turn to FIG. 8 and following for a discussion of how brace coverscan be used advantageously in such structures and systems which alsoincorporate flange braces.

Flange braces can come in a variety of sizes and shapes, but a typicalflange brace 110 is shown schematically in FIG. 8. Such a brace may bemade by bending or folding a flat piece of metal or other suitablematerial longitudinally along its length by an angle of nominally 90degrees, or another suitable angle, or by welding or otherwise joiningtwo flat pieces of metal to form a similarly angled structure. Brace 110has a first end 112 and a second end 114, which may also be referred toas an upper end and a lower end, respectively. A portion of one of theangled sides at the lower end 114 can be removed as shown in the figureto define a flat end portion which is able to bend relatively morefreely, e.g. as about the dashed line shown in FIG. 8. Holes can also beprovided in the ends as shown to allow the brace to be securelyfastened, e.g. with a bolt and nut, to different elements of thebuilding structure, such as a rafter 16 at lower end 114 of the braceand a purlin 24 at upper end 112 of the brace. In this regard, it isuseful in many cases to provide at least one hole 115A in a first angledside at one end, and at least one other hole 115B in a second angledside (which may be perpendicular to the first angled side) at upper end112. By securely fastening the ends of brace 110 to neighboring buildingelements, at appropriate positions on those elements, the brace canenhance the mechanical integrity of the structure.

A given flange brace may be characterized or described in terms of itslength, its cross-sectional shape, and by any other relevant featuresand dimensions. Braces of the type shown in FIG. 8, sometimes referredto as angle braces, are known for use in metal building construction.Such braces are made of steel, aluminum, or other suitable metals, andare available in standard sizes, e.g., 1.5×1.5 (1.5 inches by 1.5inches), or 2×2 (2 inches by 2 inches) or 2.5×2.5 (2.5 inches by 2.5inches). Such dimensions refer to the width of each of the angled sidesthat make up the angle brace, or, stated differently, to the length ofeach leg in the L-shaped cross section of the brace. Thus, for example,in one standard size, each leg of the L-shaped cross section is 1.5inches long, and in another standard size, each such leg is 2 incheslong, and so forth. The wall thicknesses of these legs, or of the angledsides, are known in the art. Such braces are available in a variety oflengths. The foregoing dimensions and features are merely exemplary, andshould not be used to unduly limit, the sizes or shapes of braces whichcan be used in the disclosed embodiments.

Alternative brace designs that may be suitable for a given buildingstructure, depending on the size of the building and the elements usedin the building structure, include braces which can be made by providinga length of hollow metal tubing, the length equal to the length of thedesired brace, each of the two ends of the tube optionally, buttypically, having been flattened, e.g. by hammering or pressing the tubeflat at the ends, including rotating the tube by nominally 90 degreesbetween effecting such flattening activities such that the flattenedends are nominally oriented perpendicular to each other. As with theembodiment illustrated in FIG. 8, holes 115A, 115B can be drilled intosuch ends to allow for attachment by nut/bolt combinations or othersuitable attachment mechanisms. The cross-sectional shape of a bracemade in this way is, over substantially all of its length except for thee.g. two flattened ends, the same as the cross-sectional shape of theoriginal metal tubing, which may be circular, square, rectangular, orother shapes as desired. With regard to angle braces and other bracesthat may have an L-shaped cross section, the term “L-shaped” should beinterpreted broadly to encompass at least embodiments in which the twolegs of the L-shape are of equal length, as well as embodiments in whichthe two legs of the L-shape are of unequal length: and embodiments inwhich the two legs of the L-shape are orthogonal (oriented at 90degrees) to each other, as well as embodiments in which the two legs ofthe L-shape are not orthogonal.

FIG. 9 shows a plate 116 that may be adapted for use with the brace ofFIG. 8. In rudimentary embodiments, the plate 116 may, by itself andwith no additional elements, serve as a brace cover 122. In other cases,other elements such as a fabric piece are attached to the plate to forma more functional and/or a more aesthetically pleasant-appearing bracecover, as discussed further below. In either case, a brace cover may beprovided for each and every brace in the building structure, for examplefor a brace which extends through the suspension fabric, i.e., for eachbrace in the building structure for which the opposed ends of the bracelie on opposite sides of the suspension fabric, or optionally a bracecover may be provided for only some such braces. The brace cover mayserve one or more basic functions, for example, to conceal the openingin the suspension fabric, to facilitate sealing around the brace, e.g.in the vicinity of the fabric opening, and/or to provide support for thesuspension fabric, e.g. near the fabric opening.

A plate aperture 118 extends through plate 116. Aperture 118 is sized soas to be able to receive brace 110. Aperture 118 is sometimes hereinreferred to as a cover opening 124, namely where there are no otherelements which form part of the cover opening besides plate 116. Thatis, plate aperture 118 has an appropriate size and shape so that an endof brace 110 can pass through aperture 118. E.g. upper end 112 of thebrace can be made to pass through aperture 118 by holding the bracestationary and moving the plate, or by holding the plate stationary andmoving the brace, or by moving both the brace and the plate. The sizeand shape of plate aperture 118 is such that e.g. end 112 of brace 110can pass through the aperture at an oblique, namely a non-perpendicular,angle corresponding to an orientation angle the brace makes with theplate in the installed system. Preferably, the aperture is not so largethat a large gap remains between brace 110, as installed, and therigid/metal or rigid/plastic portion of plate 116. Stated differently,the plate aperture preferably has a shape which is similar to across-sectional shape of the brace, e.g., a transverse cross-section ofthe brace, or a cross-section of the brace in a reference plane parallelto the aperture, as described further below. For example, in the case ofFIGS. 8 and 9, brace 110 has an L-shaped cross section, and aperture 118is also L-shaped, though larger than the cross-section of the L-shape ofbrace 110 to allow the brace to slide through plate aperture 118 withonly minimal, if any, resistance.

In alternative embodiments, plate aperture 118 can be made rectangularwhile the cross-section of brace 110 remains L-shaped, the rectangularaperture being sized so that two edges of the rectangular aperture areclose to or touching the outer surfaces of the two angled walls of thebrace. An example of this is shown below in FIG. 20B. Generallyspeaking, the plate aperture can have any desired shape, e.g. square,rectangular, another polygonal shape (including but not limited to anL-shape), or circular, oval, elliptical, or otherwise curved.Preferably, however, the plate aperture is made so that the flange brace110 fits within the aperture as installed in the building system, withonly minimalist spacing between the sides of the aperture and thesurfaces of the brace. Typically, the longitudinal axis of flange brace110 is obliquely oriented or tilted relative to a reference planedefined by the plate aperture and the plate 116 or cover 122. Thus, forexample, if the flange brace is made from a round (circular) tube whichhas been flattened on both ends, plate aperture 118 is desirably oval orelliptical, the eccentricity of the oval being determined by the angleat which the flange brace is designed to be oriented relative to theplane of brace cover 122 and plate 116. Alternatively, the plateaperture in such case may have a rectangular shape, the rectangularshape corresponding to approximately the oval cross-sectional shape ofthe round tube as the installed tube extends through the aperture, suchthat the brace still fits relatively snugly within the rectangularaperture.

Plate 116 is typically made of metal, but other suitable materials, suchas hard plastics, may also be used. However, as suggested by the term“plate”, the material used for the plate preferably has a sufficientthickness so that the plate 116 has a substantial mechanical rigidity orstiffness. The desired rigidity is preferably enough so that, when theplate, and thus the brace cover, is installed, e.g. attached to a purlinon one side of the brace, the edge of the plate on the other side of thebrace does not droop or sag, but rather provides enough support to thesuspension fabric above the plate to hold that portion of the fabric ina visually consistent orientation relative to the surrounding portionsof the fabric. In an exemplary embodiment, plate 116 is made of a singlepiece of 0.015 inch thick steel, and has a plate perimeter 120 which isnominally square, each side of the square being 12 inches long. In thisembodiment, aperture 118 is L-shaped, each leg of the aperture being 3inches long, and aperture 118 is located at or near the center of thesquare-shaped plate. Metals other than steel, such as aluminum, as wellas layered/laminated materials, can also be used in fabricating plate116. In cases where plate 116 is made of metal, a typical thickness e.g.from about 0.010 inch to about 0.050 inch, but this range should not beconstrued in an unduly limiting manner so long as the plate serves inthe above-described capacity.

The particular plate embodiment mentioned above uses a 12 inch square,e.g. each side 12 inches long, plate perimeter. Other perimeter sizesand shapes, including rectangular, polygonal, circular, or elliptical,may also be used. Whatever the shape, the overall length and/or width ofthe plate 116 is typically at least about 8 inches, or at least about 10inches, or at least about 12 inches, e.g. in order to fully conceal,and/or seal around, the opening in the suspension fabric. Further inthis regard, plate perimeter 120 is also preferably sized so that, whenthe brace cover is installed, the plate perimeter, as well as the coverperimeter, encircles the opening in that suspension fabric which thebrace extends through.

Plate 116 of FIG. 9 has a single piece construction, e.g. plate 116 ismade of a single unitary piece of metal or other suitable material. Inalternative embodiments discussed further below, plate 116 may be madeof multiple plate pieces such as two plate pieces which overlap andattach to each other to provide a rigid combination of the plate pieces,the combination having an aperture which is partially defined by a firstsuch plate piece, and partially defined by a second such plate piece.

Turning to FIG. 10, an alternative brace cover 122 is shown in anexploded view to more clearly distinguish its two main constituentcomponents. Brace cover 122, shown in FIG. 10 includes, or may consistessentially of or consist of, an apertured plate 116 as illustratedabove and a piece of fabric or other thin-section sheet material 126which is laminated to or otherwise attached to one major surface ofplate 116, e.g. with a suitable adhesive layer or other suitable bondingmaterial disposed between the fabric and the plate. The lamination offabric 126 may be performed by workers at the building constructionworksite, or may be performed in a factory or a distribution facilitybefore the brace covers are shipped to the construction site. The entirebrace cover, including apertured plate 116 and laminated fabric piece126, may be made by workers using materials and tools which areavailable at the building construction site, e.g., by making use ofexcess sheet metal and excess suspension fabric which may be present atthe construction site. Plate 116 of FIG. 10 may be the same as, orsimilar to, the plate 116 described above in connection with FIG. 9, andneeds no further explanation here.

Fabric piece 126 is preferably made of the same or similar material asthe suspension fabric 32 against which brace cover 122 is intended to beultimately placed or installed. In this regard, cover 122 is installedin the building structure such that the major surface of plate 116 whichhas no fabric applied faces generally upwardly, facing the suspensionfabric and the respective purlin, and the major surface of the platewhich does have the fabric applied, faces generally downwardly, and istypically exposed and visible to occupants of the building, against thebackground of the surrounding suspension fabric. By ensuring that thesurface of fabric piece 126 which faces toward the occupants of thebuilding has an outer appearance, e.g., color and texture, which is thesame as or similar to the appearance of the suspension fabric, the bracecovers can visually “blend in” and become inconspicuous substantiallyun-noticeable, to building occupants who look upward toward theceiling/roof. In this manner, the brace cover conceals the opening inthe suspension fabric, and may conceal any patch tape or other productswhich may have been applied at the fabric opening.

A view of brace cover 122 from below is illustrated schematically in.FIG. 11. The brace cover of that figure may be the same as or similar tothe brace cover of FIG. 10, except that the fabric piece of the bracecover is shown in its laminated state in FIG. 11. Brace cover 122, asshown in FIG. 11, may also be considered as being in an “initial state”meaning that the fabric piece 126 extends flat, and continuously, acrossplate aperture 118, with no perforations or cuts in the fabric piece 126at or in the vicinity of the plate aperture. Reference in this regard isalso made to the cross-sectional view of FIG. 12A, taken along the cutline 12A-12A in FIG. 11. The fabric piece 126 is preferably attached toplate 116 by an adhesive layer or the like such that the fabric piececovers at least the plate aperture. In the alternative, the fabric piececan be attached by any of a variety of mechanical fasteners such asscrews, rivets, nails, and the like.

In many (but not all) cases, the fabric piece covers substantially theentire major surface of plate 116 such that the perimeter of fabricpiece 126 matches the plate perimeter 120. Regardless of the coverage ofthe fabric piece over the major surface of plate 116, in at least theregion of plate aperture 118, the fabric piece is initially preferablyimperforate, i.e., without significant holes or other openings, suchthat the fabric piece seals the plate aperture. Typically, although notnecessarily, the entire fabric piece 126, not merely the portionproximate the plate aperture 118, is continuous and imperforate in theinitial state shown in FIGS. 11 and 12A. Fabric piece 126 is made of amaterial which provides a barrier to air flow, and which also preferablyprovides at least a minimal level of vapor barrier.

Besides serving a possible aesthetic purpose or function, fabric piece126 in particular facilitates sealing around the brace by more closelyconforming to the outer surfaces of the brace than does aperture 118 inplate 116, after the brace cover is fully and completely installed aboutthe brace. Stated differently, in the installed configuration, there aretypically gaps between the brace and the plate, due to portions of theplate aperture being spaced from the surface of the brace. Because thepassageway through the fabric piece is made by slitting the fabricpiece, typically without any substantial removal of material from thefabric piece, gaps between the brace and fabric piece 126 can besubstantially smaller than the gaps between the plate and the brace, dueto the conformable, flexible nature of the fabric whereby edges of thefabric readily conform to articles with which the fabric comes intocontact. In a final or near final step of installation, a sealant can beapplied around the brace, both at the suspension fabric and at the bracecover fabric, to fill such gaps, spaces in order to restore the abilityof the suspension fabric and/or the brace cover fabric (as repaired) toact as an effective vapor barrier and/or barrier to air flow.

Before the brace cover can be installed on the brace, the intact,continuous nature of the fabric piece in the vicinity of plate aperture118 is removed or eliminated by cutting a slit or other opening in thefabric piece in that vicinity. Such cut fabric is illustratedschematically in FIG. 12B, where the same brace cover 122 is shown inthe same cross-sectional view as FIG. 12A, except that the cover 122 inFIG. 12B is shown in a later state in which the fabric piece has beencut at a location underlying aperture 118, thereby providing a fabricpiece opening 128. The formation of fabric piece opening 128, byunderlying aperture 118, creates an opening through the combination ofplate 116 and fabric 126, thus through brace cover 122, such openingbeing referred to herein as a cover opening and labeled 124 in FIG. 12B.In the embodiment shown, cover opening 124 comprises both fabric pieceopening 128 and plate aperture 118. For example, air which flows throughcover opening 124 flows through both fabric piece opening 128 and plateaperture 118. In an alternative embodiment in which the fabric piece isomitted, cover opening 124 may include only, and may be the same as,plate aperture 118.

Opening 128 is depicted in FIG. 12B as a “simple slit”, which means thatsubstantially no fabric material is removed from the original fabricpiece in the process of forming opening 128, but instead, portions ofthe fabric piece 126 separate from each other to form a small openingbut otherwise remain connected to the remainder of the original fabricpiece 126. The simple slit may be made using a single, straight cut,e.g. using a sharp knife or other suitable cutting implement, or theslit may be made using a more complex cut, e.g. a T-shaped cut in whichtwo flaps are formed in the fabric piece. In alternative embodiments,opening 128 can be made by completely removing a portion of the originalfabric piece 126. For example, the fabric piece 126 can be slit in acontinuous path to completely remove a portion of the fabric piece fromthe remaining fabric piece, e.g., by slitting around the entire edge ofplate aperture 118 to define and remove a fabric portion having the sameshape, in plan view, as plate aperture 118. Compared to a fabric pieceopening 128 in which a portion of the original fabric piece 126 isremoved, a fabric piece opening 128 which is made using a simple slit,with no substantial removal of the original fabric piece, isadvantageous in that the fabric bounding such opening 128 can moreclosely conform to the outer surfaces of flange brace 110. The closerconforming fabric can help provide a more reliable seal if and when aflowable e.g. tube sealant is applied around brace 110.

Fabric piece 126 has been discussed above as being the same material assuspension fabric 32. In the alternative, fabric piece 126 can be any ofa variety of materials. The functional requirements of fabric piece 126are that fabric piece 126 provide an air barrier, and be readilypenetrable over the plate aperture in order to provide a passageway forbrace 110, through the fabric piece. Desirably, but not as a limitation,fabric piece 126 also provides a visually pleasing, or at least neutral,appearance.

As long as those minimal limitations are met, fabric piece 126 can beany of a variety of materials. The fabric piece was described above interms of being made of the same material as the suspension fabric. Thefabric piece can also be any film or sheet material, or multiple layersof film or sheet material, which collectively provide the necessaryfunctional performances. Thus there can be mentioned fabrics made ofwoven or non-woven fiber and/or plastic threads, plastic films,combinations of one or more layers of plastic film, optionally combinedand/or laminated with, one or more layers of threaded material. Threadmaterials may be any of the natural fibers, any of the polymeric fibers.As the plastic films, there can be mentioned as examples, but withoutlimitation, various of the olefin or olefin-based materials, includingolefin-based homopolymers and copolymers, such as polyethylene,polypropylene, ethylene propylene copolymer, ethylene vinyl acetates,polyamides and polyamide derivatives, acrylics, polyesters, and thelike, so long as the resulting fabric provides both a barrier to passageof air and susceptibility to being readily cut to create slit/opening128.

FIGS. 13A-13G represent a sequence of steps performed in the process ofattaching a brace to respective rafter and purlin when a one-piece bracecover 122 extends about the brace. The building structure of FIGS.13A-13G includes rafters and purlins, the purlins extending transverselyacross the rafters such that the rafters support the purlins. FIGS.13A-13G illustrate respective different steps in a process that includesinstalling a suspension fabric, attaching the brace to the purlinthrough the suspension fabric, and installing the brace cover. Relativesizes and dimensions of some of the components and features in FIGS. 13Athrough 13G, and in others of the drawings herein which are schematic innature, may not be entirely representative or typical of the relativesizes and dimensions of standard parts used in the metal buildingindustry, nor of the parts used in any particular building. Neverthelessthe drawings illustrate relevant principles involved in the installationof the disclosed brace covers.

FIG. 13A shows a portion of the building structure including a purlin 24and rafters 16. The purlin 24 is supported by the rafters and contactsthe upper surfaces 16A of the rafters. The rafters 16, which extend intoand out of the plane of the drawing and are shown in simple schematicform, define a bay 18 across which purlin 24 extends.

Purlin 24 expresses a “Z”-shaped cross-section, as shown above in FIG.6. The purlin thus has a top flange 46, a bottom flange 48, and anupstanding web 50. In a typical but non-limiting example, the verticaldimension (height or depth) of the web 50 may be 8.5 inches, and thetransverse dimension (width) of each of the flanges 46, 48 may be 2.5inches.

Rafter 16 may be an I-beam with an I-shaped cross-section as shown, butin any case the rafter includes a bottom flange 17. In a typical butnon-limiting example, the vertical dimension (height or depth) of rafter16 may be 16 inches, and the transverse dimension (width) of the entirelower flange may be 4 inches.

A flange brace 110 connects purlin 24 to rafter 16, e.g. to enhance thestructural strength, and thus the integrity, of the building structure.More particularly, flange brace 110 is securely fastened or attached tobottom flange 17 of the rafter at lower end 114 of the brace. At theupper end 112, brace 110 is securely fastened or attached to web 50 ofpurlin 24, preferably at a central location half way between top andbottom flanges 46, 48 of the purlin. The secure attachment at the endsof brace 110 may be made by an appropriately sized nut 130A and bolt130B combination, which may extend through holes 115 in brace 110 suchholes 115A, 115B being shown at both ends of the brace in FIG. 8. Othersecure attachment mechanisms can also be used, for example in some casesrivets or weld joints. However, at least the attachment of upper end 112of the brace to purlin 24 is desirably reversibly attachable, forreasons that will become apparent in the discussion which follows.

A given brace 110, and the purlin which the respective brace connectsto, may be considered a brace/purlin combination. Although brace 110 isshown as an angle brace in FIGS. 13A through 13G and FIG. 14, brace 110may have any other suitable cross-section configuration or design asdiscussed above.

In FIG. 13A, the building structure is shown in a state or conditionbefore the suspension fabric has been installed across bay 18 and whereboth the upper and lower ends of each brace are secured to therespective rafter and the respective purlin. Thus, in typical metalbuilding construction, all or substantially all, of the rafter/purlincombinations which will be braced in the respective building have hadtheir braces applied and secured before the suspension fabric isinstalled. At that stage of the construction, substantially the entiretyof the structural integrity of the building support structure which willbe provided by the braces in the finished building, has been created.

The overall objective of use of the suspension fabric is to install thefabric below the purlins and above the rafters, in such a manner thatthe fabric spans substantially the entire distance between the raftersin a given bay, even at and proximate braces 110. As the fabric isinstalled, the fabric is first generally laid out across the bay, andalong the lengths of the respective rafters. With the fabric so laid outand extending rafter-to-rafter across the bay, a given brace isindividually temporarily disengaged, and temporarily moved out of theway of the space to be occupied by the suspension fabric. The necessarywork is then done to extend that brace through the fabric, to positionand mount the cover about the brace, and to seal about the cover so asto prevent movement of air from the bottom of the fabric to the top ofthe fabric, or vice versa.

The respective braces are thus disconnected one at a time, or a few at atime, while leaving the majority of the braces fully connected to theirrespective rafters and purlins such that the building structurecontinues to benefit from the structural strength provided by thebraces, as a brace set, even while the process of installing the bracecovers, and sealing about brace covers, is taking place.

Thus, a given brace, which has first been connected to both therespective rafter at the lower end of the brace, and the respectivepurlin at the upper end of the brace, is disconnected from the purlinand moved out of the way of the fabric. After the respective portion ofthe fabric has been positioned across the space previously occupied bythat brace, the upper end of that brace is reconnected to the purlin.Typically, only after that brace has been fully re-connected to thepurlin does the respective worker or worker team move on to disconnectanother brace.

Certainly, multiple workers can be working on multiple braces in a givenbuilding at the same time. But overall, at any given point in time, mostof the braces, at both their upper and lower ends, are connected totheir respective rafters and purlins whereby the benefits of the use ofbraces remains in effect in the building structure even while the bracesare being worked through the fabric.

The invention contemplates that, in some instances, the upper ends of asmall fraction of the braces may not be connected to the respectivepurlins before the suspension fabric is installed. However, that,fraction of braces which are not installed is small enough to assure thecontractor that the building structure is adequately braced against mostweather conditions for which the building is designed, and against allof the weather conditions expected to occur before all of the braces arefully connected, both to the respective rafter and to the respectivepurlin.

FIG. 13B illustrates the first step in the process of extending a bracethrough the suspension fabric, namely where upper end 112 of the bracehas been detached/disconnected from the purlin 24, e.g. by removal ofthe nut/bolt combination 130A/130B at that end, and a worker has moved,e.g. bent, brace 110 downward at lower flange 129 so that upper end 112of the flange is below the level of the bottom of flange 48 of thepurlin. In this configuration, hole 115B in brace 110 and hole 133 inpurlin 24 which two holes were used to make the upper nut/boltattachment, are now visible. During this procedure, lower end 114 ofbrace 110 may remain connected to bottom flange 17 of rafter 16.

In FIG. 13B, upper end 112 of the brace is detached/disconnected fromthe purlin and has been lowered to an elevation below the bottom surfaceof the bottom flange of the purlin.

In FIG. 13C, the suspension fabric has been laid out and extended acrossthe respective bay 18, including in the vicinity of the brace 110. Insome instances, the fabric is laid out and extended across the baybefore any upper end of any of the braces has been detached.

In FIG. 13C, as well as in others of the drawings, the longitudinal andlateral metal bands which would normally be used to help support thefabric in spaces between rafters are not shown for simplicity andclarity of the drawings. However, such longitudinal and lateral bandsmay be included in the structure, to the extent they are needed in theparticular application as illustrated e.g. in FIGS. 2, 3, and 7. FIG.13C differs from FIG. 13B by illustrating suspension fabric 32 extendingacross bay 18 below purlins 24 and above rafters 16. FIG. 13Cillustrates a moderate amount of sag in suspension fabric 32 between therespective rafters 16. At locations where purlin 24 contacts andoverlies upper surface 16A of rafter 16, fabric 32 is notched such thatthe edges of the fabric at the notch extend along, and close to, bothsides of the bottom flange of the purlin and onto the top surface of therespective rafter 16 and the base of the notch extends along, and closeto, the near edge of the respective rafter. Such notch structure isillustrated in e.g. FIG. 17A.

With the suspension fabric extending across the bay, under the purlinsand over the respective rafters, a slit is cut in the suspension fabricnear the location of brace 110 so that brace 110 can be pushed/bent upthrough the slit in fabric 32 and re-attached to the overlying purlin.The cutting provides the slit or opening 32A in the fabric 32, showngenerally in FIG. 13D. Typically, opening 32A directly underlies bottomflange 48 of purlin 24, spaced from the inner edge of flange 48 suchthat an upward force on the fabric, such force being located immediatelyon either side of the slit, impacts directly on the bottom surface ofbottom flange 48 of the purlin. Fabric opening 32A is typically longenough, e.g. on the order of 6, 8, or 10 inches in length, so that aworker can reach both hands through opening 32A to re-attach upper end112 of brace 110 to the overlying purlin 24 with nut/bolt combination130A, 130B or other attachment mechanism.

While upper end 112 of the brace is disconnected from purlin 24 asillustrated in e.g. FIG. 13D, a brace cover 122 can be mounted about thebrace. Mounting cover 122 to the brace while upper end 112 isdisconnected is particularly important when the brace cover employs aplate having a 1-piece construction and a continuous perimeter spacedfrom an aperture which extends through the plate, such that, to installthe cover on the brace, some portion, such as the end, of the brace mustbe passed through such aperture in the plate. In FIG. 13D, forsimplicity, brace cover 122 is shown as having a plate 116 with suchaperture, such that the plate aperture 118 and cover opening 124generally describe the same passageway extending through the plate.

In other embodiments, brace cover 122 further includes a fabric piece126 mounted on plate 116 as illustrated and discussed in connection withFIGS. 10 and 11. In such cases, the brace cover may be provided in aninitial state which includes a plate and a fabric piece, the platehaving a plate aperture 118, and the fabric piece being attached to theplate such that the fabric piece covers the plate aperture, the fabricpiece being imperforate at least in a region corresponding to the plateaperture such that the fabric piece closes off passage of air throughthe opening in the plate, which opening is defined as plate aperture118. Referring to FIGS. 11, 12, and 12A, a slit 128 is formed/cut infabric piece 126 in the region corresponding to plate aperture 118, andthe unattached upper end 112 of the brace is then passed through slit128 and through plate aperture 118. The unattached end of the brace canbe made to pass through slit 128 and through plate aperture 118 byholding the brace stationary and moving the plate, or by holding theplate stationary and moving the brace, or by moving both the brace andthe plate. Of course, when the lower end 114 of brace 110 is secured tolower flange 17 of rafter 16, as is typically, but not always, the case,the passing is generally accomplished by moving plate 116 while notmoving the brace longitudinally. Although brace cover 122 is placed onthe elongate brace such that the brace extends through plate aperture118 and cover opening 124, brace cover 122 is not yet in its finalposition, e.g., the brace cover can slide, or be slid, longitudinallyalong the length of the brace as shown generally bylongitudinally-extending arrows 131 in FIG. 13D.

After the step shown in FIG. 13D, flange brace 110 is e.g. bent backupwardly to its connection point with purlin 24 at aperture 133. Inperforming this operation, upper end 112 of brace 110 is made to passthrough fabric opening 32A. FIG. 13E shows the brace passed throughopening 32A where, for example, a worker has extended his hands throughaperture 32A in the process of manipulating nut/bolt combination 130A,130B through apertures 115, 133 so as to re-attach the upper end 112 ofthe brace to web 50 of the respective purlin. After the upper end of thebrace has been so attached to the purlin, some portions of the edges offabric opening 32A are spaced from the surfaces and/or edges of brace110. At this stage, preliminary repairs or patching can be performed onthe fabric to at least partially close off such spaces about opening32A.

For example, patch tape 136 (FIG. 16D) can be applied to partially orcompletely close any gaps 138 associated with such spaces. Additionallyor in the alternative, a sealant, such as a conventional tube sealant,can be applied to partially or completely close gaps between the slitedges of suspension fabric 32 and brace 110. Such sealant is not shownin FIG. 13F, but is shown and described elsewhere herein.

After upper end 112 of brace 116 has been reattached to the purlin ataperture 133, brace cover 122 can be installed at its intended position,as shown schematically in FIG. 13F. In the case of a brace cover 122having a 1-piece plate 116, before securing upper end 112 of the braceto purlin 24, cover 122, including plate 116, is installed orpre-installed in a preliminary step by passing the then-unattached upperend 112 of the brace through plate aperture 118 and cover opening 124.Then, after the upper end of the brace is secured to the purlin,plate/cover 116/122 is slid upwardly along the length of brace 110 untilthe plate/cover contacts suspension fabric 32. Then, with a portion ofthe suspension fabric 32 disposed between plate/cover 116/112 and bottomflange 48 of the purlin, plate/cover 116/122 is pressed against, andaffixed to, the bottom flange 48 of the purlin 24, e.g. using one ormore Tek screws.

A brace cover 122 having a 2-piece plate 116, such as any of thosedescribed further below, can be installed in a similar way as the1-piece plate, except that there is no need for the preliminarypre-installlation step of passing the plate through the brace while theend of the brace is unattached. Rather, the 2-piece plate can beinstalled around the flange brace 110 even when the ends of the brace110 are secured to their respective rafter and purlin whereby the stepsof disconnecting and reconnecting the upper end of the brace from and tothe purlin can be omitted.

Finally, as shown in FIG. 13G, a suitable e.g. tube sealant 132 can beapplied about the brace at the location where brace 110 passes throughcover opening 124, thus sealing the cover opening 112 against passage ofe.g. ambient air through the cover opening.

FIG. 14 is a schematic cross-section taken along line 14-14 in FIG. 13F.FIG. 14 shows the profile of the illustrated flange brace 110 intransverse cross-section, i.e., in a plane oriented perpendicular to thelongitudinal axis of the brace. Brace 110, as illustrated, has anL-shaped cross-section, wherein the legs of the “L” are of nominally thesame length. The illustrated brace profile is merely exemplary, andbraces having other profiles in transverse cross-section can also beused as discussed above.

FIG. 15 is a schematic cross-section taken along line 15-15 in FIG. 13F.From this perspective, the cross-section profiles of both the top 46 andbottom 48 flanges of purlin 24, as well as web 50 of the purlin, can beseen. Also, FIG. 15 shows brace 110 extending through fabric opening32A, with upper end 112 on one side of the opening and lower end 114 onthe other side of the suspension fabric. A nut/bolt combination 130 a,130B is positioned to secure upper end 112 of the brace to web 50 ofpurlin 24. A ring of sealant 134 is disposed between brace cover 122 andsuspension fabric 32. Sealant ring 134 is shown in further detail inFIG. 18E, discussed following. One lateral side of brace cover 122 issecured to bottom flange 48 of the purlin, e.g. using Tek screws 66 orother suitable screws or attachment mechanism. The other lateral side ofbrace cover 122 is cantilevered or otherwise suspended, laterally awayfrom bottom flange 48 of the purlin and contacts and supports a portionof suspension fabric 32 by virtue of the rigidity or stiffness providedby the e.g. metal or hard plastic properties of plate 116. With respectto the gaps which can be seen in FIG. 15 between brace 110 and bracecover 122, tube sealant 132 shown in FIG. 13G is applied to fill suchgap. FIG. 15 is modestly inconsistent with FIG. 13F to the extent FIG.15 depicts brace cover 122 as including a fabric piece 126, while thebrace cover shown in FIG. 13F does not.

FIG. 16A is a schematic cross-section taken along line 16A-16A of FIG.13F, and thus is taken to show a bottom view, looking up, of plateaperture 118 and/or plate 116 and/or brace cover 122. Due to the tiltangle of the brace 110 relative to brace cover 122, theupstanding/vertical leg 140 of brace 110 in FIG. 16A is elongated in thedirection of the tilt, relative to the horizontal leg. Thus, when viewedfrom a perpendicular angle, in cross-section, the lengths of legs 140,142 are equal. But when viewed from a non-perpendicular angle as in FIG.14, the legs of the brace are no longer appear to be equal in length,and the thicknesses of legs 140, 142 no longer appear to be equal. Forthis reason, plate aperture 118 may similarly appear to be elongated inthe elongate direction of the purlin relative to the cross-sectionalprofile of brace 110 when viewed from a non-perpendicular angle.

FIGS. 16B and 16C are schematic cross-sections similar to FIG. 16A butfor alternative brace cover embodiments. In the embodiments illustratedin FIGS. 16B and 16C, the brace cover includes a fabric piece 126 morefully illustrated in FIGS. 10, 11, 12A and 12B. According to the coverembodiments illustrated in FIGS. 16B and 16C, a fabric piece opening128, e.g. an L-shaped slit, conforms relatively closely to the profileof brace 110 as the brace passes through cover 122 at anon-perpendicular angle. Plate aperture 118 of FIG. 16C is larger, e.g.the aperture legs are larger than the plate aperture in FIG. 16B, e.g.to accommodate any of a variety of flange braces of different leglengths.

FIGS. 17A-17C illustrate a sequence of schematic views which lookdownward on a portion of a building structure from a plane which passesthrough two purlins below their upper flanges, illustrating from thedownwardly-looking top perspective, some of the same steps illustratedherein from a side perspective in FIGS. 13A-13G. Referring back to FIGS.17A-17C, top flanges 46 of the respective purlins are not shown in FIGS.17A-17C in order to better show notches 144 in the fabric at theintersections of the purlins and the rafters. FIGS. 17A through 17Cillustrate how building elements including rafters, purlins, andsuspension fabric 32 appear from this vantage point. FIGS. 17A-17Cparticularly show how the fabric overlies, and can be attached to,rafters 16, while notches 144 enable the fabric to lie in a continuouslygenerally planar configuration at the locations where the purlinsoverlie the rafters.

FIG. 17A illustrates a step similar to that shown in FIG. 13C, where thefabric has been extended across the bay between first and second rafters16 and along the lengths of the rafters under multiple purlins 24. InFIG. 17A, the ends of the fabric at the bottom of the drawing shownotches 144 having been cut into the edge of the fabric at theintersections where the fabric overlies the rafter. Legs of the notchesextend generally parallel to the length of the purlin, slightly spacedfrom the purlin and on either side of the bottom flange 48 of thepurlin. The base of the notch extends generally parallel to the lengthof the rafter, slightly spaced from the edge of the flange of therafter, on the bay side of the rafter.

Also in FIG. 17A, ends of the fabric at the top of the drawing show thestress in the fabric before any notches have been cut in the fabric andwhere the fabric has been stretched onto the rafter.

FIG. 17B illustrates a step similar to that shown in FIG. 13D, whereslit/opening 32A, shown as dashed lines, has been cut in the fabricunderlying bottom flange 48 of the purlin. In FIG. 17B, notches 144 havealso been cut into the edge of the fabric at locations where the purlinsoverlie the rafter at the top of the drawing.

FIG. 17C illustrates a step similar to that shown in FIG. 13E, whereupper end 112 of brace 110 extends through slit/opening 32A in thefabric. At that step, hole 115 in the upper end of the brace is alignedwith hole 133 in web 50 of the purlin, and bolt 130B and nut 130A areshown ready for bolt 1308 to be inserted through holes 115 and 133 thusto re-attach the upper end of the brace to the purlin web.

FIGS. 18A-18G show a sequence of schematic views which look upward at aportion of a suspension fabric in a building near a location on a purlinwhere a flange brace is attached to the purlin. FIGS. 18A-18G illustratehow the suspension fabric and related building elements appear from thisvantage point during multiple steps in a process which includesattaching a flange brace to the purlin through the suspension fabric andinstalling a brace cover.

FIG. 18A shows a stage in the process of attaching a flange brace to thepurlin through the underlying suspension fabric, similar to the stageshown in FIG. 13B, and wherein the outline of the elements of theoverlying purlin, shown in FIG. 18A, are shown with dashed lines.

FIG. 18B shows a stage in the process of attaching a flange brace to thepurlin through the underlying suspension fabric, similar to the stageshown in FIG. 13C, and where slit/opening 32A has been cut in thefabric, the slit/opening having been cut in the fabric at a locationwhich underlies lower flange 48 of the purlin.

FIG. 18C shows a stage in the process of attaching the flange brace tothe purlin through the underlying suspension fabric, similar to thestage shown in FIG. 13E, and where the brace is extending up throughslit/opening 32A. FIG. 18C shows, particularly, that one side edge 146of the slit/opening has been moved past the purlin web in order toextend the brace through the slit/opening 32A beside purlin web 50. Asillustrated in FIG. 18C, the transverse movement of the one side 146 ofthe slit/opening away from the opposing such side creates a substantialpassageway 148 for movement of e.g. ambient/cold air from e.g. the upperside of the fabric to the lower side of the fabric whereby suchpassageway presents a potential path for entrance of ambient air intothe space enclosed inside the respective building. As suggested in FIG.18C, and as obvious from use of bolt 130B and nut 130A, thevertical/upstanding leg of the brace is typically tight againstupstanding web 50 of the purlin when secured to the purlin by nut 130Aand bolt 130B. And even with the brace tight against the purlin web,opening 32A represents a potential path for convective movement of coldair into the building.

FIG. 18D shows a stage in the process similar to that of FIG. 18C, wherefirst and second pieces/lengths of tape 136 have been applied to thelower surface of fabric 32, the lengths of the pieces of tape extendingalong the length of the overlying purlin. The pieces of tape have beencut/fabricated such that the ends of the tape which are close to brace110 fit closely against the major surfaces of the brace where the braceextends through the fabric. As illustrated in FIG. 18D, the pieces oftape close off the majority of the cold air passageway/path created byextending brace 110 through slit/opening 32A. Thus, the tape functionsas a first line of defense against movement of cold air throughpassageway 148.

In an embodiment not shown, after brace 110 has been inserted throughslit/opening 32A as illustrated in FIG. 18C, and before tape 136 hasbeen applied, slit/opening 32A is modified by creating a transverse cut,starting from the slit/opening, typically extending perpendicular to thelength of the slit/opening shown in FIG. 18B. The transverse cut is madeat the location where the horizontal leg of the brace passes through thefabric. The transverse cut creates two e.g. right angle corner pieceswhich can be used to close off most of the passageway between the remoteedge of the horizontal leg of the brace and the web of the purlin. Withthose corner pieces lying generally in the plane of fabric 32, theopening represented by passageway 148 is substantially reduced in size.With the passageway so reduced in size, there is less passageway for thetape to close off, and the tape can attach to the right angle cornerpieces much closer to the sides of the horizontal leg of the brace.

FIG. 18E shows a stage in the process similar to that of FIG. 18D, wherea line of tube sealant has been applied to the bottom surface of fabric32, completely surrounding passageway 148 and thus defining a closedloop of such sealant 134 about the passageway. In the illustratedembodiment, the closed loop also extends outwardly of the pieces of tapesuch that the tape pieces are disposed entirely within the closed loopof sealant represented as 134. For reasons illustrated hereinafter, itis desired that as much of the closed loop of sealant as possible bepositioned underlying bottom flange 48 of the purlin, and that portionof the sealant which does not underlie the bottom flange be close to thebottom flange, however outside the edges of tape pieces 136. The closedloop of sealant is also shown, in cross-section, in FIG. 15.

FIG. 18F shows a stage in the process similar to that of FIG. 18E, wherethe brace cover 122 has been mounted to the bottom flange of the purlinusing e.g. Tek screws 66. The stage shown in FIG. 18F as anupwardly-looking view is similar to the step shown in elevation view inFIG. 13F. FIG. 18F shows approximately a first half of the brace coverextending to one side of web 50 and approximately a second half of thebrace cover extending to the opposing side of the web. Screws 66 aredriven tight into the bottom flange of the purlin whereby the screwshold the respective underlying portion of the brace cover tight againstthe bottom flange of the purlin whereby force urging the upper surfaceof the brace cover against the lower surface of the purlin bottom flangetightly engages a frictional entrapment of the fabric between the uppersurface of the brace cover and the lower surface of the bottom flange ofthe purlin. The portion of the rigid brace cover which underlies thefabric under the upper flange of the purlin is cantilevered from thetight attachment of the brace cover to bottom flange 48, whereby thecantilevered portion of the brace cover extends from web 50 in agenerally horizontally-extending plane, allowing for the slope of theoverlying roof, thus the tops of the rafters.

At this stage of the process of installing the brace covers through thefabric, the fabric is typically stretched into a generally taught,generally horizontal orientation. With both the fabric and thecantilevered portion of the brace cover being in generally horizontalorientations, with the fabric trapped between the brace cover and thebottom flange of the purlin, and with the fabric subject to a modestdrape due to the force of gravity, the cantilevered portion of the bracecover and the overlying portion of the fabric are extending generallyparallel to each other and in surface-to-surface contact with eachother.

Given the tight entrapment of the fabric between the brace cover and thebottom flange of the purlin and the parallel contacting surfaces of thefabric and the cantilevered portion of the brace cover, and withapplication of a thick enough bead of the tube sealant, the entirety ofthe closed loop of sealant 134 bridges the distance between fabric 32and brace cover 110 about the entirety of the closed loop of sealant.Thus, the closed loop of sealant provides a second line of defenseagainst movement of cold air through passageway 148 and into theinterior of the building.

Accordingly, any cold air which manages to get past tape 136 atpassageway 148 is prevented from entering the enclosed space of thebuilding by lateral movement between brace cover 110 and fabric 32, bydosed loop 134 of tube sealant.

FIG. 18G shows a stage in the process similar to that of FIG. 18F, wherean additional application of tube sealant 132 has been applied to thebottom surface of the brace cover at the location where brace 110 passesthrough the brace cover. Such application of tube sealant provides aflexible bridge into and across the spaces between cover opening 118,124 and the surfaces of brace 110. The application of tube sealant 132is the same sealant shown in elevation view FIG. 13G. As suggested inFIG. 13G, tube sealant 132 can extend entirely through aperture/opening118, 124 in brace cover 122, and may reach and bond to tape 136 and/orfabric 32. Tube sealant 132 thus prevents passage of cold air throughaperture/opening 118, 124 in brace cover 122, whereby tube sealant 132provides a third line of defense against passage of cold/ambient airinto the enclosed space inside the building.

Accordingly, the invention provides three lines of defense againstinfiltration of ambient air into the space enclosed by the building. Thefirst line of defense is tape 136 which closes off most of passageway148 at the fabric. The second and third lines of defense preventsubstantially all passage of any residual air which gets past tape 136,into the space enclosed by the building. Closed loop 134 preventsmovement of such residual air into the building by way of transversepaths between the fabric and the brace cover. Tube sealant 132 preventsmovement of such residual air into the building by way ofaperture/opening 118/124 in brace cover 122.

FIGS. 19A and 19B are upwardly-looking plan views of a 2-piece plate foruse as or in the disclosed brace covers, FIG. 19A shows the two platepieces 116A, 1168 separated from each other, with flange brace 110positioned between the plate pieces. FIG. 19B shows the upstanding legof brace 110 in surface-to-surface contact with web 44 of the purlin. Asubstantial portion of plate piece 116A overlies plate piece 1168, thusentrapping the brace between the two plate pieces at aperture 118. Thetwo plate pieces joined to each other to form a two-piece plate havingaperture 118, with the flange brace extending through the aperture andwhere the outline of the aperture generally conforms to thecross-section profile of the flange brace. The plate pieces are shownbeing fixedly held to each other in FIG. 19B by screws or rivets 150. Ifscrews 150 are used to join the two plate pieces, the same screws canextend through both of the first and second plate pieces, and throughbottom flange 48 of the purlin thus, as shown, mounting the brace coverto the purlin bottom flange with the same screws which are used to mountthe two plate pieces to each other.

FIGS. 20A and 20B are upwardly-looking plan views similar to FIGS. 19Aand 19B but for another embodiment of a 2-piece plate. FIG. 20A showsthe two plate pieces 116A, 116B separated from each other, with flangebrace 110 positioned between the plate pieces. FIG. 20B shows theupstanding leg of brace 110 in surface-to-surface contact with web 50 ofthe purlin. A substantial portion of plate piece 116A overlies platepiece 116B, thus entrapping the brace between the two plate pieces ataperture 118. The two plate pieces are joined to each other to form atwo-piece plate having aperture 118, with the flange brace extendingthrough the aperture and where the outline of the aperture differssubstantially from the cross-section profile of the flange brace. Theplate pieces are shown being fixedly held to each other in FIG. 20B byscrews or rivets 150. The embodiment of FIGS. 20A, 20B finds particularutility in providing cover plate pieces which will accommodate a widevariety of flange brace cross-sections.

FIGS. 21A and 21B are upwardly-looking plan views similar to FIGS. 19Aand 19B but for still another embodiment of a 2-piece plate. In theembodiment of FIGS. 21A, 21B, plate piece 116A has a recess whichaccommodates the upstanding leg of brace 110, and plate piece 116B has arecess which receives the transversely-extending leg of brace 110. FIG.21A shows the plate pieces spaced from each other with brace 110 betweenthe two plate pieces.

FIG. 21B shows the upstanding leg of brace 110 in surface-to-surfacecontact with web 50 of the purlin. A small portion of plate piece 116Aoverlies plate piece 1168, thus entrapping the brace between the twoplate pieces at aperture 118. The two plate pieces are joined to eachother by screws or rivets 150 to form a two-piece plate having aperture118, with the flange brace extending through the aperture and where theoutline of the aperture substantially conforms to the cross-sectionprofile of the flange brace. The thus-assembled 2-piece plate is shownas having been mounted to bottom flange 48 of the purlin by screws 66.Thus, the two-piece plate of FIG. 21B employs both screws/rivets 150 andscrews 66.

FIG. 22 is an upwardly-looking plan view of another embodiment of2-piece plates. In the embodiments illustrated in FIG. 22, the two platepieces are pivotably connected together by a pivot pin 152 so that platepiece 116A can rotate relative to plate piece 116B as indicated bydouble-headed arrow 153, and a detent mechanism 154A, 154B or othercapture structure is provided to temporarily lock two pieces together,until screws 66 can be driven through both plate pieces and the bottomflange of the purlin, thus to secure the closed combination closed, andto secure the cover plate to the bottom flange of the overlying purlin.

Two piece plate covers illustrated in FIGS. 19-22 have the advantage ofnot needing to be mounted to the flange brace before the upper end ofthe flange brace is extended through fabric 32.

Although the invention has been described with respect to variousembodiments, the invention is also capable of a wide variety of furtherand other embodiments within the spirit and scope of the appendedclaims.

Those skilled in the art will now see that certain modifications can bemade to the apparatus and methods herein disclosed with respect to theillustrated embodiments, without departing from the spirit of theinstant invention. And while the invention has been described above withrespect to certain preferred embodiments, the reader will readilyunderstand that the invention is adaptable to numerous rearrangements,modifications, and alterations, and all such arrangements,modifications, and alterations are intended to be within the scope ofthe appended claims.

To the extent the following claims use means plus function language, itis not meant to include there, or in the instant specification, anythingnot structurally equivalent to what is shown in the embodimentsdisclosed in the specification.

What is claimed:
 1. A building roof structure, comprising: (a) raftersand purlins, the purlins extending transversely across the rafters suchthat the rafters support the purlins; (b) a suspension fabric extendingacross said roof structure such that said suspension fabric extendsacross tops of said rafters and below said purlins; (c) bracesconnecting at least some of said purlins to at least some of saidrafters, each brace and the respective said purlin to which such braceconnects defining a brace/purlin combination, and each brace extendingthrough a corresponding suspension fabric opening in said, suspensionfabric; and (d) for each of at least some of the brace/purlincombinations, a brace cover having a cover opening through which thebrace extends, the brace cover being disposed such that a portion of thesuspension fabric is between the brace cover and the purlin.
 2. Astructure as in claim 1 wherein, for at least some of said brace/purlincombinations, said purlin has a lower flange, and said brace cover isattached to said lower flange of said purlin.
 3. A structure as in claim1 wherein, far at least some of said brace/purlin combinations, saidpurlin has a central web disposed between a purlin upper flange and apurlin lower flange, and said brace is attached to said central web ofsaid purlin.
 4. A structure as in claim 1 wherein at least some of saidbrace/purlin combinations further comprise a sealant applied around saidbrace and optionally into the cover opening in order to provide abarrier against ambient air flow through the cover at the cover opening.5. A structure as in claim 1 wherein, for at least some of saidbrace/purlin combinations, said brace cover has a perimeter whichencompasses the suspension fabric opening.
 6. A structure as in claim 5wherein at least some of said brace/purlin combinations further compriseone or more pieces of tape applied to said suspension fabric to patch,to thereby at least partially close, the suspension fabric opening.
 7. Astructure as in claim 5 wherein a sealant bridges and seals a spacebetween said brace cover and said suspension fabric.
 8. A structure asin claim 7 wherein said sealant defines a closed loop path, spaced fromthe suspension fabric opening, which closed loop path encompasses thesuspension fabric opening.
 9. A structure as in claim 8 wherein aperimeter of said brace cover defines closed loop path which encompassesthe closed loop path of said sealant.
 10. A structure as in claim 1wherein, for at least some of said brace/purlin combinations, said bracecover comprises a plate, and said plate has a plate aperture which formsat least a portion of the cover opening.
 11. A structure as in claim 10wherein said plate of at least one of said brace covers has a 1-piececonstruction.
 12. A structure as in claim 10 wherein said plate of atleast one of said brace covers has a 2-piece construction.
 13. Astructure as in claim 12, wherein each plate which has the 2-piececonstruction has a first plate piece attached to a second plate piece,and the plate aperture in each such plate is partially defined by saidfirst plate piece and partially defined by said second plate piece. 14.A structure as in claim 10 wherein the plate aperture has a firstL-shaped profile and, when said plate and brace are installed such thatsaid plate is attached to the associated said purlin and said brace isattached to the associated said rafter and purlin, the plate aperturedefines a reference plane, and a cross-section of said brace in thereference plane has a second different L-shaped profile.
 15. A structureas in claim 10 wherein said brace cover of at least some of saidbrace/purlin combinations also comprises a fabric piece attached to saidplate and, when installation of said brace cover has been completed, thecover opening further comprises a fabric piece opening in said fabricpiece, further comprising a sealant applied at a junction of said braceand said brace cover at the cover opening and optionally into the coveropening in order to provide a barrier against ambient air passingthrough the cover opening.
 16. A structure as in claim 10 wherein saidcover plate has first and second opposing major surfaces, the firstmajor surface facing said purlin, and wherein said brace cover furthercomprises a fabric piece which covers the second major surface of saidplate.
 17. A building roof structure, comprising building structuralroof elements including at least first and second rafters, a spacebetween said first and second rafters defining a first distance betweensaid first and second rafters, each said rafter having a top, andopposing first and second ends, said roof structure further comprisingan eave, having a length, and extending between the first ends of saidfirst and second rafters, a ridge, having a length, and extendingbetween the second ends of said first and second rafters, and a seconddistance between said eave and said ridge, said eave and said ridgebeing disposed on, extending transverse to, and being connected to, thetops of said first and second rafters, and a plurality of intermediatepurlins extending between said first and second rafters and spaced fromeach other between said eave and said ridge, said intermediate purlinsbeing disposed on, and extending transverse to the tops of said firstand second rafters, the building roof structure further comprising: (a)a first set of support bands extending from said first rafter to saidsecond rafter and being connected to said building structural roofelements, said first set of support bands being spaced along the lengthsof said first and second rafters; (b) a second set of support bandsextending from said eave toward said ridge and under said intermediatepurlins, said second set of support bands having first and second endportions and being spaced from each other between said first and secondrafters; (c) a suspension fabric overlying, and being supported by, saidfirst and second sets of support bands, said suspension fabric beingsecurely attached to structural members of said building; (d) aplurality of braces which collectively connect at least some of suchintermediate purlins to one or both of such first and second rafters,each brace extending through a corresponding fabric opening in thesuspension fabric; and (e) for each brace which connects a given saidpurlin to a given said rafter, a brace cover having a cover openingthrough which the respective said brace extends, said brace cover beingattached to the given said purlin and having a perimeter which encirclesthe fabric opening through which said brace extends.
 18. A brace coversuitable for use in a building roof structure which includes buildingroof structure braces, said brace cover comprising: (a) a plate having athickness of at least 0.01 inch, and having an L-shaped aperture, theL-shaped aperture having a first leg at least 1.5 inches long and asecond leg at least 1.5 inches long, such that the L-shaped aperture issized to receive a building roof structure brace; and (b) a fabric pieceattached to the plate such that the fabric piece covers the aperture,the fabric piece also being imperforate at least in a regioncorresponding to the aperture such that the fabric piece seals theaperture.
 19. A brace cover as in claim 17 wherein said second layer isimperforate.
 20. A method of fabricating a building roof structure,comprising: (a) providing an initial building structure which includescolumns, rafters supported by the columns, purlins supported by therafters, and braces which connect at least some of the rafters to atleast some of the purlins, each brace having an upper end which attachesto an associated purlin; (b) detaching the upper ends of the braces fromthe associated purlins; (c) laying out a suspension fabric across theroof structure above the rafters and below the purlins; and (d) for agiven brace, (i) cutting a suspension fabric opening in the suspensionfabric near the brace and the associated purlin, thereby to define acover opening; (ii) guiding the upper end of the brace through thefabric opening in the suspension fabric, and re-attaching the upper endof the brace to the associated purlin; and (iii) attaching a brace coverto the associated purlin with a portion of the suspension fabricdisposed between the brace cover and the purlin, the brace cover havinga cover opening through which the brace extends.
 21. A method as inclaim 20 wherein, for a given brace, the attaching comprises passing theupper end of the brace through the cover opening before re-attaching theupper end of the brace to the associated purlin.
 22. A method as inclaim 21 wherein the method further comprises, before the attaching thebrace cover to the associated purlin: providing the brace cover in aninitial state, the brace cover in the initial state including a plateand a fabric piece, the plate having a plate aperture, and the fabricpiece being attached to the plate such that the fabric piece covers theplate aperture, the fabric piece being imperforate at least in a regioncorresponding to the plate aperture such that the fabric piece seals theplate aperture against free flow of ambient air through the fabricpiece; and slitting the fabric piece in the region corresponding to theplate aperture to provide the cover opening.
 23. A method as in claim 20wherein the method further comprises, for a given brace, afterre-attaching of the upper end of the brace to the associated purlin, andbefore attaching the brace cover to the associated purlin, sliding thebrace cover upwardly along the brace toward the associated purlin.
 24. Amethod as in claim 20, further comprising, for a given brace, assemblingthe brace cover about the brace and thereby defining a brace coveropening through which the brace extends.
 25. A method as in claim 24wherein, for a given brace, the brace cover comprises a plate having aplate aperture, the plate aperture being at least a portion of the coveropening, the plate also having a 2-piece construction comprising a firstplate piece and a second plate piece, and wherein the assembling of thebrace cover about the brace comprises joining the two plate pieces toeach other and thereby forming the plate aperture about the brace.
 26. Amethod as in claim 20 wherein each brace cover has a perimeter andwherein, for a given brace, the attaching of the brace cover to theassociated purlin comprises positioning the brace cover so that theperimeter of the brace cover encompasses the fabric opening.
 27. Amethod as in claim 20, further comprising, for a given brace, sealingthe brace cover to the suspension fabric using a sealant in a closedloop path which is laterally spaced from the fabric opening and whichencompasses the fabric opening.
 28. A method as in claim 20, furthercomprising, for a given brace, sealing the cover opening from ambientair flow by applying a sealant at a junction of the brace and the bracecover at the cover opening and optionally into the cover opening inorder to provide a barrier against ambient air flow through the coveropening.
 29. A method of installing a brace cover on a brace in relationto a building roof structure, the method comprising: a) providing abrace cover in an initial state, the brace cover in the initial stateincluding a plate and a fabric piece, the plate having a plate aperture,and the fabric piece being attached to the plate such that the fabricpiece covers the plate aperture, the fabric piece being imperforate atleast in a region corresponding to the plate aperture such that thefabric piece seals the plate aperture; (b) providing a brace having afirst end; (c) forming a slit in the fabric piece in the regioncorresponding to the plate aperture; and (d) passing the first end ofthe brace through the slit and through the plate aperture.
 30. Themethod as in claim 29 wherein the brace has a second end opposite thefirst end, and wherein the second end is secured to building roofsupport structure under the building roof structure during the passingof the first end of the brace through the slit and through the plateaperture.
 31. A suspension fabric kit, comprising: (a) a length ofsupport banding suitable for extending a first set of support bands froma first rafter of a building to a second rafter of such building, and asecond set of support bands, for crossing said first set of supportbands and extending from an eave of such building, under intermediatepurlins, to a ridge of such building; (b) a suspension fabric suitablefor extending from such first rafter to such second rafter and from sucheave to such ridge, with said first and second sets of support bandingsupporting said suspension fabric; and (c) a plurality of brace coversadapted and configured to extend about braces which are secured to onesof such rafters and ones of such purlins, and wherein such braces extendthrough apertures in said brace covers. said brace covers, incombination with sealants applied to said brace covers, bridging edgesof the brace cover apertures and surfaces of such braces, and therebyproviding a barrier against flow of ambient air through the respectivecover apertures.